1. Field of the Invention
The subject invention is directed to a broadhead hunting arrow wherein the cutting blades are in a fully retracted position within a cylindrical body during the flight of the arrow. Upon striking the quarry, the cutting blades are opened and locked in an extended position.
2. Description of the Prior Art
Broadhead hunting arrows have been used for many years for hunting game animals such as deer. A broadhead is a particular type of arrow head which has outwardly extending blades that are designed to inflict more extensive damage to the animal. An objective for any broadhead is to have the animal killed as quick as possible such that the animal will not suffer for a long period of time and so that the animal will be recoverable by the hunter. Hunting regulations require broadheads to be of a specific size that will ensure killing the animal quickly such that the hunter does recover his quarry and will report the kill to the game warden. Broadheads having smaller than the legal width generally do not inflict as much damage and result in slower bleeding. The illegal broadheads do not kill the animal as fast, yet they do mortally wound the animal; hence, the hunter using the illegal broadhead typically loses his prey and does not report the kill. Accurate harvesting records which reflect all kills ensure better wildlife management.
Today's hunting arrows typically comprise a fiberglass or graphite shaft on which the broadhead body is threadably mounted. In many prior art broadheads, the blades are secured on the arrow in a fully open position, i.e., they are clipped to the sides or integrally formed with the body that is secured to the arrow shaft. It has been found that the flight of the arrow is adversely affected by wind resistance acting against the exposed broadhead blades. For example, broadheads with fixed blades tend to be less accurate because of wind current deflection and tend to have less velocity because of increased drag. Therefore, design efforts for modern broadheads typically have focussed on decreasing the wind effects to ensure a more accurate and effective broadhead.
U.S. Pat. No. 4,504,063 to LeBus discloses a broadhead hunting arrow which is designed to have the blades positioned in a narrower profile during flight and to have the blades moved to an expanded position when the arrow strikes the animal. A plunger tip positioned at the front of the broadhead moves towards the blades upon impact and causes a mass connected at the opposite end of the plunger to move within the hollow body and act against an inside surface of each of the blades. The inside surface of the blades is shaped such that the mass forces the blades outward when the plunger is forced rearward. One problem with the LeBus broadhead is that it is designed to always have some portion of the blades exposed; therefore, the effects of wind resistance are not completely avoided. Another problem with the LeBus broadhead is that there is no provision for preventing the main stem from riding up on the plunger and causing the blades to open during flight. Today's bows typically launch an arrow at a rate of 250 feet per second (fps) which may be a speed sufficient to cause the blades to open simply by the dead weight inertia of the mass within the hollow body relative to the quickly moving shaft.
U.S. Pat. No. 2,859,970 to Doonan discloses an arrow head designed to have cutting blades retracted within a cone at the front of the arrow during flight, yet have the cutting blades open upon impact with the animal. Doonan discloses that having fully retracted blades during flight avoids the adverse wind effects such as deflection of the arrow in an undesired direction and decreased flight velocity; however, problems with the Doonan arrow head would make it unacceptable for today's bow equipment. Doonan shows a cone shaped unit positioned on the front of an arrow with a target point. The cone can be held on the end of the shaft with a frictional fit or by riding in grooves on the shaft of the arrow. A pair of cutting blades are secured to a pivot pin within the cone body. The cutting blades are bowed slightly such that they will be frictionally held within the slots of the cone body during flight. The target point of the arrow acts as a camming surface against the backside of the retracted blades and forces the blades open when the animal is struck by the arrow.
One problem with the Doonan design is that it relies on the arrow shaft to open the blades. In today's equipment, the broadhead is threadably secured to the arrow shaft, not frictionally fit on the front end of a target arrow; therefore, there is no way for the shaft to provide any camming action against a pair of retracted blades. Moreover, Doonan's frictional fit design may allow a deer to pull the arrow shaft, without the cone shaped tip, out of its body after being struck, thereby closing the wound and decreasing the bleeding. With a modern, threaded together, broadhead hunting arrow, the deer could not pull the shaft out of its body without also pulling out the broadhead.
Another problem with the Doonan design is that the amount of frictional engagement between the slightly bowed cutting blades and the slots in the cone shaped body is not easily regulated and may be insufficient to hold the blades in their retracted position during flight. Moreover, an arrow shot at 250 fps should have sufficient velocity to open the blades fully in flight, i.e., Doonan's arrow head would not work with modern equipment since the target arrow head would be driven into the backside of the blades simply by the speed and force of today's bows.
The Forrestline company is currently selling a broadhead called the Punchcutter.TM. which is designed with a pair of blades held in a fully retracted position during flight. Upon striking an animal, the blades are opened 90.degree. from the retracted position. The blades are positioned within a cylindrical body on a pivot pin located closer to the arrow shaft than the arrow tip. The Punchcutter.TM. design has led to very unsatisfactory results. Since the blades open from a backward orientation to a 90.degree. angle, the blades are pushed rather than pulled through the animal. As a result, the broadhead does not penetrate through the animal and causes less extensive damage than desired; hence, a number of deer have been mortally wounded with the Punchcutter.TM. but have not been retrieved by the hunter.